Assorted

Some functions for missing data:

• apop_data_listwise_delete
• apop_ml_impute

A few more descriptive methods:

• apop_matrix_pca : Principal component analysis
• apop_anova : One-way or two-way ANOVA tables
• apop_rake : Iterative proportional fitting on large, sparse tables

General utilities:

• Apop_stopif : Apophenia's error-handling and warning-printing macro.
• apop_opts : the global options
• apop_system : a printf-style wrapper around the standard system function.

A few more math utilities:

• apop_matrix_is_positive_semidefinite
• apop_matrix_to_positive_semidefinite
• apop_generalized_harmonic
• apop_multivariate_gamma
• apop_multivariate_lngamma
• apop_rng_alloc